Daily-worn frame glasses are composed of lenses and a spectacle frame. Currently, the material used for manufacturing the lenses mostly are glass, resin, etc. In the glasses industry, there are strict requirements for the optical properties of the material of the lens, e.g. transmittance, refractive index and dispersion, etc. Among them, the refractive index of the lens plays a decisive role for the thickness of the lens.
For example, myopia glasses are simple optics for vision correction or eye protection, which use the principle of concave lens such that the image of an object becomes closer, thus a myopia patient wearing the myopia glasses can see the distant object clearly. On one hand, for the same lens material, the higher the degree of myopia is, the stronger the lens is, and the bigger the thickness of the lens is. One the other hand, for the same degree of myopia, the bigger the refractive index of the lens is, the smaller the thickness of the lens is.